Focus Detection Pixel Layout for Phase Difference Autofocus
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Solution Overview
Problem
Current image sensor devices face challenges in accurately performing autofocus using phase difference detection, as existing focus detection pixels are not optimized in size and configuration to effectively detect phase differences between signals, leading to inefficiencies in light sensing and focus positioning.
Innovation Solution
The integration of a focus detection pixel pair with a photosensitive unit and a photo-insensitive unit, disposed opposite to each other with respect to the optical axis of a lens, allows for simultaneous light incidence without blocking, enabling the detection of side-looking information to determine focus position through phase difference autofocus, with the option of varying sizes and configurations to enhance detection capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detection pixels are disposed among image sensing pixels for phase difference autofocus, then autofocus capability is enabled, but light sensing efficiency and focus positioning accuracy deteriorate due to non-optimized size and configuration
Solution Approach 1:
The focus detection pixel is segmented into distinct functional regions including a photosensitive unit for detecting light beams and a photo-insensitive unit for receiving light without sensing. This segmentation allows each unit to be optimized for its specific function, improving phase difference detection accuracy while maintaining a manageable device structure.
Solution Approach 2:
Different regions within the focus detection pixel are assigned different optical properties - the photosensitive unit has light-sensing capability while the photo-insensitive unit has light-receiving but non-sensing properties. This local differentiation of quality enables effective phase difference measurement by comparing signals from regions with different optical characteristics.
2Productivity
If photosensitive unit and photo-insensitive unit are disposed opposite to each other with respect to optical axis, then simultaneous light incidence is enabled without blocking, but manufacturing precision requirements increase
Solution Approach 1:
The photosensitive unit and photo-insensitive unit are positioned asymmetrically with respect to the optical axis, with each unit located on opposite sides. This asymmetric arrangement allows light beams to incident simultaneously on both units without mutual blocking, optimizing light sensing efficiency while the optical axis serves as a reference for manufacturing alignment.
Solution Approach 2:
The focus detection pixel structure is designed to serve multiple functions: the photosensitive unit detects light for phase difference measurement, the photo-insensitive unit receives light without sensing to provide reference signals, and together they enable both autofocus and potential image sensing capabilities within a unified pixel structure.
3Measurement precision
If focus detection pixels use equal or larger sizes compared to image sensing pixels, then detection capabilities are enhanced, but device area and manufacturing complexity increase
Solution Approach 1:
The focus detection pixel utilizes a two-dimensional arrangement of photosensitive and photo-insensitive units within the pixel area, with units positioned at different locations relative to the optical axis. This dimensional arrangement allows enhanced detection capability through multiple light reception paths while efficiently utilizing the available pixel area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the accuracy and efficiency of autofocus by effectively detecting phase differences, improving focus detection and positioning, while potentially simplifying manufacturing processes and reducing costs by using equal or larger sizes for focus detection pixels compared to image sensing pixels.
Implementation Method 1
the photosensitive unit detects the light beam
Data Source
AI summary
A photosensitive unit and a photo-insensitive unit are formed in a substrate. A lens is formed to cover the photosensitive unit and the photo-insensitive unit, and the lens has a single radius of curvature and an optical axis passing through a surface of the curvature at the center of the lens. The photosensitive unit is disposed at a first side of the optical axis and the photo-insensitive unit is disposed at a second side opposite to the first side of the optical axis, a light beam passing through the lens is simultaneously incident into the photosensitive unit and the photo-insensitive unit without being blocked, and the photosensitive unit detects the light beam while the photo-insensitive unit is ineffective in sensing the light beam. A conductive feature is formed over the substrate between the photosensitive unit and the photo-insensitive unit, wherein the optical axis of the lens passes the conductive feature.